OTTAWA— Human swine flu is hospitalizing three to four times as many children than regular seasonal influenza, new data from a nationwide surveillance system shows.

Since October, 526 H1N1-related hospitalizations were reported by 12 pediatric teaching hospitals across Canada that together represent almost 90 per cent of all tertiary care pediatric beds in the country.

During the week of Nov. 7 alone, 264 children were hospitalized — about half the total number of Canadian children hospitalized during last year's entire flu season, and three to four times as many flu-related admissions during any week since the network began collecting data five years ago.

At the Children's Hospital of Eastern Ontario in Ottawa, as of Wednesday, 108 children had been admitted with laboratory-confirmed H1N1 since the beginning of the second wave of H1N1 in early October.

That compares to 40 children admitted during the entire 2007-08 flu season, and 37 children admitted during the 2006-07 flu season.

In the first wave of pandemic H1N1 this spring, 32 children were admitted to CHEO with confirmed H1N1.

"Children across Canada are being hospitalized in very large numbers for influenza this year, much larger than anything we've ever seen before," says Dr. Wendy Vaudry, a pediatric infectious disease specialist at the University of Alberta in Edmonton and co-principal investigator of IMPACT, an immunization monitoring program administered by the Canadian Paediatric Society and funded by the Public Health Agency of Canada.

"It is causing significant illness in children all across Canada."

Vaudry, a mother of four, said vaccination is the best way to protect children against H1N1. "If I were a parent hearing this, I'd walk out this afternoon and go to your closest clinic and get your baby immunized," she said.

It is not yet known how many children admitted to hospital during the second wave have required intensive care. Normally, about 15 per cent of children admitted with flu end up in intensive care. It is also not yet known how many of them had underlying health conditions.

Usually the majority of flu admissions in children are in children under age two. But older children are being hospitalized with H1N1.

"We're seeing more children in the two to five, and five to nine age groups than we usually do in a normal flu season," Vaudry says.

Federal officials said Wednesday that while the number of H1N1 cases is "levelling off" in some parts of the country, the peak of the second wave has not yet been reached. And they warned Canadians about becoming complacent.

Fewer positive flu tests and fewer outbreaks in schools were reported by the provinces and territories in the past week, two key indicators used to monitor the pandemic.

But the numbers remain well above normal for this time of year. In the last few weeks, for example, the rate of people who sought medical attention for flu-like symptoms was four to seven times higher than usual.

"In reaching the plateau of the second wave in some communities, it does not mean the pandemic is over," Dr. David Butler-Jones, Canada's chief public health officer, said Wednesday. "There is still the other side of the peak and there remain millions of infections to be prevented."

B.C. entered its second wave of the pandemic sooner than other provinces and, while it is still reporting a high number of hospitalizations, it was lower in the past week than in the previous week.

About 15 million doses of H1N1 vaccine will have been shipped to the provinces by the end of this week, and many jurisdictions are now immunizing the general population, and not just high-priority groups.

Butler-Jones warned about the possibility of a third wave of infections.

BEGINOPTIONALTRIM

"Even after a large second wave many people will not still have been infected, they will remain susceptible to the virus, making following waves possible," he said during a new briefing.

He estimated that five to 10 per cent of the population has already been infected, and that about 25 per cent have been immunized.

ENDOPTIONALTRIM

As of Tuesday, 279 deaths linked to the H1N1 virus had been reported to the Public Health Agency of Canada.

BEGINOPTIONALTRIM

Vaccination campaigns got underway on Oct. 26. At that time, most provinces targeted people with underlying health conditions and young children first.

Children who received the vaccine in the first round could expect to have produced an immunity against the pandemic virus by mid-November. Vaudry said it's too soon to tell what impact the vaccine is having on hospital admissions for flu.

"But we do know that this vaccine is for the right strain of influenza. That's often the biggest issue — how well the influenza vaccine is going to work. This vaccine is made for this specific strain, so it should be very effective."

Since the beginning of the pandemic in April, six deaths due to H1N1 had been reported through the IMPACT network among children under 16 years of age.

In total, as of Nov. 14, 1,138 children under 16 had been hospitalized with H1N1 since Apr. 26.

END OPTIONALTRIM

BEGINOPTIONALEND

Warning signs that a child should be taken to a doctor include any difficulty breathing, sleepiness or not being as responsive as usual, for babies, not drinking or feeding well, and a fever of 39 C or more.

Meanwhile, U.S. health officials Wednesday responded to media reports about a West Virginia pediatrician and her son who were infected twice with lab-confirmed H1N1.

"That is not impossible. That can happen," Dr. Anne Schuchat, director of the National Center for Immunization and Respiratory Diseases at the Centers for Disease Control and Prevention, said in a media briefing.

"We don't think that's a common event in a population, but that there are some reasons why an individual might not get protected after one natural infection and might be at risk for a future infection with the same strain." It is possible their bodies did not develop an adequate antibody response to the virus the first time around.

She also said no vaccine is 100 per cent protective. In clinical trials, the H1N1 vaccine "looked very good," she said, and provided a good antibody response eight to ten days later, "but it wasn't 100 per cent.

"So it's possible that after a natural infection or after the vaccine some people might get it again . . . or get if for the first time if you're vaccinated," she said.

Almost Done!

Postmedia wants to improve your reading experience as well as share the best deals and promotions from our advertisers with you. The information below will be used to optimize the content and make ads across the network more relevant to you. You can always change the information you share with us by editing your profile.

By clicking "Create Account", I hearby grant permission to Postmedia to use my account information to create my account.

I also accept and agree to be bound by Postmedia's Terms and Conditions with respect to my use of the Site and I have read and understand Postmedia's Privacy Statement. I consent to the collection, use, maintenance, and disclosure of my information in accordance with the Postmedia's Privacy Policy.

Postmedia wants to improve your reading experience as well as share the best deals and promotions from our advertisers with you. The information below will be used to optimize the content and make ads across the network more relevant to you. You can always change the information you share with us by editing your profile.

By clicking "Create Account", I hearby grant permission to Postmedia to use my account information to create my account.

I also accept and agree to be bound by Postmedia's Terms and Conditions with respect to my use of the Site and I have read and understand Postmedia's Privacy Statement. I consent to the collection, use, maintenance, and disclosure of my information in accordance with the Postmedia's Privacy Policy.